Self-adjusting wrench



Nov. 26, 1940. v L. c. MEAb 2,223,306

SELF-ADJUSTING WRENCH Filed June 15, 1939' l I 18 I 17 ....%m..&= ATTORNEY I INVENTOR Q L. c ea Patented Nov. 26, 1940 PATENT OFFICE 'S ELF-ADZIUSTING WRENCH.

Lawrence C. Mead, Whittier, Calif.

Application June 13, 1939, Serial No. 278,880.

4 Claims.

This invention relates to self-adjusting or socalled speed wrenches of that type in which rotation of the handle relative to the jaws controls the movement of the jaws relative to each other, and is a continuation in part of my copending application for Patent Serial No. 252,408 filed January 23, 1939.

The main object of the invention is to so construct a wrench of this type that diiferent holding powers for nuts of different sizes is automatically provided, which is so arranged that small nuts are better held from slipping than has previously been the case, while any tendency to break the wrench when operating on large nuts f is almost entirely eliminated,-

A further object is to arrange and proportion the jaws so that all nutsyvithin the range of the wrench will be engaged for the full length of one side by the pressure jaw without said jaw ever projecting beyond a nut. By this means, the wrench may be conveniently used in close quarters.

The wrench is particularly designed for use with hexagon nuts, and another object of the invention is to shape and arrange the jaws so that a nut of any size will always be engaged on three sides and definitely locatedin the wrench, so that slipping of the nut is avoided.

Also, the wrench is constructed so that the jaws have a wide range with a relatively small handle movement.

A further object of the invention is to produce a simple and inexpensive device and yet one which will be exceedingly effective for the purpose for which it is designed.

These objects I accomplish by means of such structure and relative arrangement of parts as will fully appear by a perusal of the following specification and claims.

In the drawing similar characters of reference indicate corresponding parts in the several views:

Figure 1 is a side view of the wrench'showing the jaws in a relatively closed position.

Figure 2 is a similar view, partly in section,

' showing a small nut held by the jaws.

Figure 3 is a similar view showing a large nut being gripped.

Figure 4. is an enlarged fragmentary section on line 4-4 of Fig. 1.

Referring now more particularly to the characters of reference on the drawing, the body of the wrench comprises a pair of spaced side plates I each having a straight outer edge 2. Integral win and bridging the plates and extending outwa-rdly from the edge 2 for about half the length thereof is the fixed jaw 3, whose working side is formed with two nut-engaging faces I and 5 disposed at 120 to each other.

The face 4 which is nearest the edge 2 is disposed at an angle of 120 thereto, and is somewhat longer than the other face 5, and also so as to be at least as long as one side of the largest hexagonal nut adapted to be handled by the wrench.

Overhanging plates I and slidably supported on the edges 2 beyond jaw 3 is the movable jaw 6, whose working face is disposed at 120 to edge 2, or so that it is parallel to the outermost face 5 of jaw 3. The tip of jaw 6 is disposed adjacent and not outwardly of a line L drawn parallel to edge 2 through the point of intersection of the sides 4 and 5 with each other. The jaw 6 is formed with a shank l disposed between the body plates l and having an outer straight edge 8 parallel to edge 2 and slidably engaging the underside of the jaw 3, which is preferably alined with edges 2 as shown.

Projecting from between the plates I in a. direction away from the jawsis a handle 9, pivotally mounted onthe plates by a rivet IQ of special form as will be seen later. This rivet is located on the plates beyond a line drawn at right angles to the point of intersection of edge 2 with the adjacent jaw face 4, in a direction away from the movable jaw, as indicated in Fig.2. v

The shank 1 is formed with a deep U-shaped notch H cut upwardly from its lower edge, the median line of said notch inclining upwardly in the direction of the outer end of the movable jaw as shown. The handle, above pivot I0, is formed with a tooth or cam IE to engage the notch, one face of the cam, which is the working face 13 and is the innermost one relative to jaw ,fiQbeing rounded, while the opposite or outer edge is straight, so that a sharp edge or point is formedat the apex of the cam. At the base of the cam, the handle member is formed with convex rounded shoulders M. The inner edge of the notch at the base is also rounded into the lower edge of the shank as at Hi. The cam and. notch are designed and shaped to cooperate with each other in such a manner'that the apex of the cam and some portion of the curved face are always in contact with certain points in the notch. In this manner, while the handle may have a long sweep or are of movementbetween its limits of travel, there will be no slack between the fixed and movable jaws, and the shank of the movable jaw of course travels in a straight line.

The working face l6 of the notch above rounded edge I5 is concavely curved and is so disposed relative to the working face of the cam, that the handle, when turned in a direction to close the jaws, will move increasing amounts with constant amounts of movment of the movable jaw toward a closed position.

It will also be seen that the cam with movement of the handle in said direction, gradually approaches what may be considered as a dead center position relative to the working face'of the notch. In other words, when the jaws are in a fully closed position, a radial line through pin H] to the point of engagement'of the working face l3 of the cam with the notch face I6 is then closer to right angular relation to said working face of the notch than at any other point in the travel of the handle and cam. This obviously means that itis harder for the jaws to be spread when engaged with a small nut N than with a large nut N This is because the turning movement imparted to the'cam from the working face of the notch by the spreading tendency imparted to the movable jaw by a small nut held between the jaws, is then less than when the jaws are more widely spread and the angular relation between the working face of the notch and the radial line of the cam is more acute. As a result, the wrench has the desired automatic increase in holding power as the nuts engaged by the wrench become smaller.

The curved shoulders M, with swinging of the handle from one side to the other, roll in close contact with the lower edge of the shank, thus helping to hold the shank against tipping movement as it slides back and forth. When the cam is substantially symmetrical with the median line of the notch, the point of the cam engages the bottom of the notch. The above features eliminate the need for any special guide channels for the movable jaw such as are ordinarily employed, and which are expensive to mill.

The use of a single cam and notch to' give the desired change of holding power as the jaw moves enables the result to be obtained without loss of strength, and yet without having to make the shank and other parts heavy and cumbersome.

With either large or small nuts, the jaws never project beyond the nuts, on account of the relative arrangement of the working faces of the jaws as previously described, so that the wrench can be used in close quarters with any sized nuts, and yet with all nuts held with equal efiiciency.

In order to normally turn the handle relative to the body so that the jaws are moved to a relatively closed position, and so that a nut when engaged will also be automatically gripped with a certain pressure, I provide a spiral spring I I. This is disposed about one end of the rivet I0 outwardly of the adjacent body plate I, and at one end is secured to the rivet while the other end depends clear of said plate and is anchored in the handle as shown in Fig. 4.

In order to enclose the spring and protect the same from damage, the adjacent end of the rivet is formed with an enlarged fiat head'or cap l8, which overhangs and extends beyond the edge of the plate from which the handle attached end of the spring depends. The rivet is arranged so as to be stationary with the body plates, and turns in the handle. This enables the head to be welded on the plate if desired, adding strength, while the bearing portion of the rivet is better protected from becoming worn and loosened by abrasive dust.

Since the working face of the movable jaw inclines away from its base in the direction of the same end of the edge 2 toward which the handle turns when operated to tighten a nut, such nut is better held against slipping than if the jaw faces were at right angles to the edge 2, or sloped in the opposite direction.

From the foregoing description it will be readily seen that I have produced such a device as substantially fulfills the objects of the invention as set forth herein.

While this specification sets forth in detail the present and preferred construction of the device, still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the invention, as defined by the appended claims.

Having thus described my invention, what I claim as new and useful and desire to secure by Letters Patent is:

1. In a self-adjusting wrench which includes spaced body plates, a fixed jaw rigid with the plates, a movable jaw cooperating with the fixed jaw, a handle projecting from between the plates and operatively connected to the movable jaw and a pin pivotally mounting the handle on the plates, said pin at one end projecting outwardly from one plate; a spiral spring about said projpecting end of the pin anchored'at one end on the pin and at the other end on the exposed portion of the handle immediately adjacent said one plate and an enlarged head on said end of the pin overhanging and enclosing the spring.

2. In a self-adjusting wrench which includes spaced body plates, a fixed jaw rigid with the plates, a movable jaw cooperating with the fixed jaw, a handle projecting from between the plates and operatively connected to the movable jaw and a rivet pivotally mounting the handle in connection with the plates and fixed against rotation therein, said rivet projecting outwardly from one plate, a spiral spring on the plate about the projecting end of the rivet, said spring being fixed at one end against movement relative to said plate and at the other end depending over the adjacent side edge of the plate to an anchorage in'the handle, and a head on the adjacent end of the rivet extending over and enclosing the spring and overhanging said edge of the plate and the depending end of the spring.

3. A self-adjusting wrench comprising a body, a fixed jaw projecting outwardly from the body, a movable jaw mounted on the body for movement in a straight line toward and from the fixed jaw, a shank depending from the movable jaw, a handle pivoted on the body below the shank, the latter having a relatively deep notch cut up from its lower edge and a cam on the handle engaging the notch whereby with arcuate movement of the handle the movable jaw will move in said straight line, said cam being formed with a point at its end farthest from the handle pivot,

and the notch being rounded at the bottom; the,

depth of the notch being such relative to the length of the cam as to cause the cam point to contact with the notch through the full arcuate movement of the cam and handle.

4. A self-adjusting wrench comprising a body, a fixed jaw projecting from the body, a movable jaw mounted on the body for movement in a straight line toward. and from the fixed jaw, a

shank depending from the movable jaw, a handle pivoted on the body below the shank, said shank able jaw along said straight line with arcuate' movement of the handle; one side of the cam being straight and facing in the direction of the movable jaw and the opposite side being convexly curved and making a point junction with the straight side, the sides and point of the cam being so disposed relative to the wall of the notch as tocause the point of the cam to contact with said wall throughout the arcuate'movemerit of the cam and to have additional contact either with the straight or curved side of the cam.

LAWRENCE C. MEAD. 

